The midwife resigned on Friday in the wake of claims the hospital has been understaffed and that nurses have been working double shifts.

At least one other midwife has also left the Berri Hospital in recent months and several nursing positions have remained vacant following staff resignations.

Concerns have been raised that midwives are being rostered on to ward duties while also caring for women in active labour.

Hospital staff met with union representatives last week to discuss concerns raised in recent months about understaffing, overtime, insufficient skills mix of nurses rostered on during shifts, a failure by management to respond to concerns raised in staff surveys and lack of admininstrative support.

"As of late last week, I am aware that at least one midwife has in fact resigned as a result of the failure of CHSA to provide resources and supports that would enable her to meet her professional obligations to women and their babies under her care," Elizabeth Dabars from the Australian Nursing and Midwifery Federation SA branch said today.

"[Last week] I met with nurses and midwives at the Berri Hospital, many of whom were in tears and some speaking of resignation as a direct consequence of their inability to meet basic care needs of their patients.

"Concern [was raised] that instances of 'missed care' will result in patient harm.

"Despite raising these concerns, CHSA has continued to deny or have grossly underplayed the validity of these issues.

"Peculiarly, CHSA have continually asserted that they monitor the situation regularly, but then refuse to provide us with the very information that they are relying on to assert that there are no systemic issues."

A union bid to obtain data on nursing and patient numbers at the Berri and Naracoorte hospitals has been taken to the Industrial Relations Commission this afternoon.

Country Health SA has denied claims that Berri Hospital has been understaffed and patient care compromised.

"Each hospital regularly holds nursing and midwifery forums where staff are encouraged to raise any concerns or issues they might have to ensure they are properly addressed," CHSA chief executive Belinda Moyes said.

"At the last forum the feedback provided to management indicated that while staff are busy, they are not overwhelmed."